Homogenization is a fluid mechanical treatment that involves the subdivision of particles or droplets into uniform sizes to create a stable dispersion or emulsion for further processing. Perhaps most associated with the dairy industry, homogenization involves forcing milk, an oil-in-water emulsion, under high pressure through a tiny orifice, thereby decreasing the average diameter and increasing the number and surface area of the fat globules in the milk. The net result is a much reduced tendency for creaming of the fat globules. Further, homogenized milk has better taste, an improved shelf life, and a reduced number of preservatives are usually needed.
Homogenization of fluids other than milk is also common. For example, food and feed products are often homogenized before spray drying to ensure the best quality powders are produced. This can be particular important for baby foods, as well as other easily masticatable food products. Homogenization is also essential to the quality and stability of many cosmetics, perfumes, beauty creams, lotions, nail varnishes, soaps, shampoos, and toothpastes. The pharmaceutical industry also makes wide use of homogenization to formulate APIs (Active Pharmaceutical Ingredients) into ointments, emulsions, syrups, liquids, and controlled release preparations.
Pressure-based homogenization techniques are quite common and are typically used in the dairy and food industries. Such techniques involve a special device that contains a homogenizing valve. As fluid is forced under high pressures through a minute gap in the homogenizing valve, conditions of high turbulence, pressure, cavitation, and shear are created. These conditions cause the disintegration of the particles or droplets throughout the fluid. Oftentimes, the product is then pass through a second valve similar to the first, which further separates any remaining clumps or clusters of the particles or droplets. After homogenization, the particles or droplets are usually of reduced and uniform size (e.g., 0.1 to 5 μm, depending on the particular operating procedures).
Whether one uses pressure-based homogenizing techniques or some other homogenizing technique (e.g., sonication-based techniques and mechanical-based techniques), three main factors contribute to the enhanced properties of a homogenized fluid such as milk: a decrease in the mean diameter of the particles or droplets in the fluid, a decrease in the size distribution of the particles or droplets (causing the speed of rise to be similar for the majority of particles or droplets such that they don't tend to cluster during creaming), and an increase in density of the particles or droplets (bringing them closer to the continuous phase).
Many products that are homogenized during preparation are also desirable compositions in which to incorporate microencapsulated materials. For example, dairy products could be fortified with microcapsules containing various nutritional supplements. Lotions, creams, and other cosmetics could be formulated to include microencapsulated materials such as pigments, conditioners, moisturizers, UV-blocking agents, etc. Pharmaceutical preparations are also possible recipients for microencapsulated products. While these and other products could be valuable and beneficial products, homogenizing conditions are typically too harsh for microencapsulated materials. As such, adding microcapsules to various products is not done, or is done only after homogenization. And adding microcapsules after homogenization can be undesirable. For example, plant processes may have to be redesigned in order to add microcapsules after homogenization. This can be particularly costly when the final product is sterilized or pasteurized.
In light of the desire for homogenized formulations that contain microcapsules, what are needed are methods for preparing such formulations, as well as formulations prepared by such methods. The subject matter disclosed herein meets these and other needs.